1. Field of the Invention
The present invention relates to solid state image sensors and, more particularly, to a solid state image sensor which includes at least an image sensor section having an array of a plurality of pixels arranged in the horizontal and vertical directions in a two-dimensional matrix fashion, a vertical scanning means for selecting one horizontal line of the image sensor section as a line for reading out a signal from a pixel and a horizontal scanning means for reading out signals of pixels of the thus read-out horizontal line in a constant order.
2. Description of the Prior Art
As conventional solid state image sensors, there is known such a solid state image sensor which at least includes an image sensor section having an array of a plurality of pixels arranged in the horizontal and vertical directions in a two-dimensional matrix fashion, a vertical scanning circuit for selecting one horizontal line of the image sensor section as a line for reading out a signal from a pixel and a horizontal scanning circuit for reading out signals of pixels of the thus read-out horizontal line in a constant order. Signals of respective pixels of the horizontal line selected by the vertical scanning circuit are read out to the respective vertical signal lines, and are suppressed with respect to noise by a correlation double sampling circuit. Then, the signal of one horizontal line is read out to the horizontal signal line in a constant order by the horizontal scanning circuit.
Such a conventional solid state image sensor reads out the signal in a manner entirely different from that of a CCD (charge coupled device) type solid state image sensor in which signal charges read-out from pixels are transferred in the vertical and horizontal directions by the shift register.
The conventional CCD type solid state image sensors include an electronic shutter function. A principle of electronic shutter is to substantially redlace an electric charge storage time by discharging signal electric charges during one portion of the electric charge storage period.
It is desirable that the solid stage image sensor in which signals of respective pixels of the horizontal line selected by the vertical scanning circuit are read out to respective vertical signal lines and signals of respective vertical signal lines are read out to the horizontal signal line by the horizontal scanning circuit in the constant order be provided with the electronic shutter function. However, the principle of electronic shutter of the CCD type solid state image sensor cannot be applied to the solid state image sensor of the aforesaid type as it presently exists.